I have tried MIG wedling a steel JIC fitting to the input nipple on my fuel rail. Both Rail and fitting are steel. Not the tidies of welds but seems to be good. Problem is that as soon as I put fuel pressure to the rail now the weld seems to leak. I can't seem to find any pin holes and each time I try re-welding the area that looks like it is leaking it still leaks.

Anyone got any suggestion of tips for stopping this leak as I don't really want to buy a new rail as it's not available as a seperte part

Is the way I am welding it causing the joint to be porus or do I keep creating small pinholes each time I weld?

Is there a better way to weld it that MIG?

I'd have tried brazing it on....or got a plumber mate to do it...

Have you tried purging the rail with welding gas before welding ? I'm no expert (and therefore may be talking cr*p), but it might be drawing oxygen into the weld from the back ?

I would try grinding most of the weld off again. This can reveal pinholes. Then burn each pinhole with the mig. Test and repeat.

we used silver solder on our fuel rail and it worked a treat